Canadian Patent Application A1 2,084,967 describes solid acid catalysts wherein a hydrocarbon chain with a pendant sulfonic acid group is bonded to a silicon. These catalysts are not of a high acid strength and at high temperatures have stability problems.
Perfluorosulfonic acid catalysts, for example perfluoropolymers containing pendant sulfonic acid groups (e.g., NAFIONO.RTM. catalyst sold by E. I. du Pont de Nemours and Company) are excellent catalysts for a wide variety of reactions. Perfluoropolymers containing pendant sulfonic acid groups are very strong acids and are used in reactions such as acylations, carbonylations, condensations, alkylations, esterifications, etherifications, hydrations, nitration, isomerizations and oligomerizations. These reactions have been reviewed extensively in "Catalysis with Nafion.RTM.", F. J. Waller, R. W. van Scoyac, Chem. Tech., 1987, 17, 438-441 and in "Perfluorinated resin sulfonic acid (Nafion.RTM. -H.sup.+) Catalysis" in Synthesis, G. A. Olah, P. S. Iyer and G. K. Surya Prakasch, 1986, 513-531. A drawback to the commercial use of perfluorocarbon sulfonic acid catalysts has been their high cost and relatively low catalytic activity, for some reactions, such as alkylations in non-polar solvents.
WO95/19222 describes a solid acid microcomposite catalyst which comprises a perfluorinated ion-exchange polymer containing pendant sulfonic and/or carboxylic acid groups entrapped within and highly dispersed throughout a network of metal oxide.
EP 582879 describes shaped organosiloxane condensates, processes for their preparation and use. These organosilanes, however, are not based on perfluorosulfonic acids which are known to have higher acid strength.
The present invention provides the benefits of increased stability, reduced costs, and in some cases higher catalytic activity and improved reaction selectivity over catalysts mentioned above.